Struct MigrationPlan 

pub struct MigrationPlan<'a, const N: usize> {
    pub policy: MigrationPolicy,
    pub steps: [MigrationStep<'a>; N],
    pub step_count: usize,
    pub old_size: usize,
    pub new_size: usize,
    pub copy_bytes: usize,
    pub zero_bytes: usize,
    pub backward_readable: bool,
}

A generated migration plan between two layout versions.

Contains ordered steps to transform V(N) account data to V(N+1). All steps are stack-allocated to stay no_std/no_alloc.

Fields

policy: MigrationPolicy

steps: [MigrationStep<'a>; N]

step_count: usize

old_size: usize

Old total size.

new_size: usize

New total size.

copy_bytes: usize

How many bytes must be copied from old to new.

zero_bytes: usize

How many bytes are newly zero-initialized.

backward_readable: bool

Whether V(N) code can still parse V(N+1) accounts (prefix-compatible).

Implementations

impl<'a, const N: usize> MigrationPlan<'a, N>

pub fn generate(older: &'a LayoutManifest, newer: &'a LayoutManifest) -> Self

Generate a migration plan from two manifests.

Analyzes the field-level diff and produces an ordered list of concrete steps (copy prefix, zero-init new fields, update header).

pub fn len(&self) -> usize

Number of steps in the plan.

pub fn is_empty(&self) -> bool

Whether the plan has no steps.

pub fn requires_data_copy(&self) -> bool

Whether this plan requires data movement (non-trivial migration).

pub fn step(&self, i: usize) -> Option<&MigrationStep<'a>>

Get step by index.

pub fn for_each_step<F: FnMut(usize, &MigrationStep<'a>)>(&self, f: F)

Iterator-style: iterate steps with index.

Trait Implementations

impl<'a, const N: usize> Display for MigrationPlan<'a, N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.